Journal of the Korean Society for Precision Engineering

Dynamic Characteristic-based Driving Performance Analysis of a Semi-active Suspension Wheel Module for Small Mobile Robots: Seoyeon Park, Sungjae Kim, Juhyun Pyo, Murim Kim, Jin-Ho Suh; J. Korean Soc. Precis. Eng. 2025;42(11):919-926.
Published online November 1, 2025; DOI: https://doi.org/10.7736/JKSPE.025.069

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This study details the development of a semi-active suspension wheel module for small mobile robots and assesses its dynamic characteristics under various driving conditions through simulation. The wheel module features a low-degree-of-freedom mechanical design and includes a semi-active damper to improve adaptability to different environments. To validate the simulation model, a prototype robot equipped with the wheel module was created, and obstacle-crossing experiments were conducted to measure vertical acceleration responses. The model was then refined based on these experimental results. By employing design of experiments and optimization techniques, the effective range of damping coefficients was estimated. Additionally, simulations were carried out at different speeds, payloads, and obstacle heights to identify optimal damping values and examine their trends. The results indicate that the proposed module significantly enhances driving stability and can serve as a foundation for future control strategies in robotic mobility systems.

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Suspension Mechanism Design of a Low-platform Target Robot for Evaluating Autonomous Vehicle Active Safety: Jae Sang Yoo, Do Hyeon Kim, Jayil Jeong; J. Korean Soc. Precis. Eng. 2024;41(5):375-381.
Published online May 1, 2024; DOI: https://doi.org/10.7736/JKSPE.024.024

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As advanced driver-assistance systems become more common in commercial vehicles, there is a growing need for evaluating safety of vehicles. Low platform target robot systems play a crucial role in this evaluation process as they can assess safety performances of autonomous vehicles. Driving stability of a target robot during real vehicle tests depends significantly on its suspension system. Therefore, developing an appropriate suspension device for the target robot is of utmost importance. This study aimed to improve driving stability by comparing two different suspension configurations: a single rocker and a double rocker, both incorporating a crank rocker mechanism. Initially, a two-dimensional model that met constraints of the suspension device was developed, followed by an analysis of reaction forces. Subsequently, an optimal design was determined using design of experiments principles based on parameters of a 2D model. The manufactured suspension system model based on the optimal design underwent multi-body dynamics simulation to evaluate driving stability. Comparative analysis of driving stability for both configurations was performed using MBD simulation, offering insights into the superior suspension design for the target robot.

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Active Suspension Control Using Reinforcement Learning: Do-Gyeong Yuk, Jung Woo Sohn; J. Korean Soc. Precis. Eng. 2024;41(3):223-230.
Published online March 1, 2024; DOI: https://doi.org/10.7736/JKSPE.023.141

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In recent years, research on machine learning techniques that can be integrated with existing suspension control algorithms for enhanced control effects has advanced considerably. Machine learning, especially involving neural networks, often requires many samples, which makes maintaining robust performance in diverse, changing environments challenging. The present study applied reinforcement learning, which can generalize complex situations not previously encountered, to overcome this obstacle and is crucial for suspension control under varying road conditions. The effectiveness of the proposed control method was evaluated on different road conditions using the quarter-vehicle model. The impact of training data was assessed by comparing models trained under two distinct road conditions. In addition, a validation exercise on the performance of the control method that utilizes reinforcement learning demonstrated its potential for enhancing the adaptability and efficiency of suspension systems under various road conditions.

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Control Characteristics of Active Suspension in Vehicles using Adaptive Control Algorithm
Jeong Seo Jang, Jung Woo Sohn
Transactions of the Korean Society for Noise and Vibration Engineering.2024; 34(5): 568. CrossRef
Suspension Mechanism Design of a Low-platform Target Robot for Evaluating Autonomous Vehicle Active Safety
Jae Sang Yoo, Do Hyeon Kim, Jayil Jeong
Journal of the Korean Society for Precision Engineering.2024; 41(5): 375. CrossRef

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Development of Steering Stop Parts for Automobile Suspension Using Former Cold Forging Complex Forming Technology: Dong-Hwan Park, Seong-Chul Han, Seung-Ho Han, Hyuk-Hong Kwon; J. Korean Soc. Precis. Eng. 2023;40(1):57-64.
Published online January 1, 2023; DOI: https://doi.org/10.7736/JKSPE.022.079

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Steering Stop parts constituting the suspension system of automobiles are located inside an automobile suspension. They are used to fix upper and lower suspension arm parts by welding. The purpose of this study was to develop Steering Stop parts for automobile suspension. Cost increase due to problem of existing tool life is a challenging issue. This study tries to solve the tool life problem and reduce the cost using a former cold forging complex forming technology. We developed a long-life complex forming technology between multistage former forging and cold forging for producing Steering Stop parts of automobile suspension.

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Mathematical Modeling and Analysis for the Ejection Force of Pyrotechnic Suspension System: Jung Pil Kim, Gu Hyun Ryu, Joon Kim, Jae Seung Yoo; J. Korean Soc. Precis. Eng. 2021;38(7):513-520.
Published online July 1, 2021; DOI: https://doi.org/10.7736/JKSPE.021.036

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The main function of aircraft ejection system is that it separates the store from the aircraft. The ejection force is important for the safety of the aircraft when the store is ejected, because the store can be lifted by air flow affected by the aircraft’s speed. If the ejection force is low, the aircraft can be damaged by the floating store. The ejection force of the suspension system should be designed in order to release the store safely. In this study, the ejection force of the pyrotechnic suspension using the cartridge to eject the store was researched. This research was performed, based on the precedent study about the over-center linkage mechanism and the pressure drop by the orifice. The ejection force was calculated, after analyzing mathematical fundamentals about the pressure in the system of the suspension and analyzed through AutoDyn and ADAMS software. Finally, the theoretical results were compared with the ejection test results of the suspension system.

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Slip Analysis and Experimental Verification for an Omni-Directional Mobile Robot based on Mecanum Wheels: Seolha Kim, Cheonghwa Lee, Baeksuk Chu; J. Korean Soc. Precis. Eng. 2020;37(1):35-42.
Published online January 1, 2020; DOI: https://doi.org/10.7736/JKSPE.019.082

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In this study, slip phenomenon that occurs during trajectory tracking motion of an omni-directional mobile robot based on Mecanum wheels was analyzed. Mecanum wheels which generate the omni-directionality to the mobile robot comprise a centered rim wheel and passive sub-rollers. In forward and backward motion, they function like usual wheels to enable rolling along the ground. However, in sideways motion, they create lateral motion of the mobile robot from the rotational actuation using their peculiar structural configuration, during which slip of the sub-rollers occurs. Unnecessary over-slip of the sub-rollers causes tracking errors of the mobile robot motion. To analyze the properties and reasons for the slip phenomenon, squared and circular trajectory tacking experiments were performed. From the experiments, it was observed that sideways motion generated respectively larger tracking errors than forward and backward motion. The geometric analysis regarding the tracking error generation was discussed using the Mecanum wheel structure. Finally, it was confirmed that suspension mechanism to provide four Mecanum wheels of the mobile robot with even reaction forces on the ground is necessary.

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Auxetic and Holonomic Mobile Robot for Enhanced Navigation in Constrained Terrains
Cheonghwa Lee, Jinwon Kim, Hyeongyeong Jeong, Hyunbin Park, Baeksuk Chu
Journal of Field Robotics.2025; 42(8): 4414. CrossRef
Development of Pipe Robot by Using Mecanum Wheels
Daeyoung Kim, Soonwook Park, Hojoong Lee, Jongpil Kim, Wonji Chung, Dohoon Kwak
Journal of the Korean Society of Manufacturing Process Engineers.2021; 20(2): 58. CrossRef
Mobile Robot Overcoming Narrow Space Using Negative Poisson’s Ratio
Jinwon Kim, Hyeongyeong Jeong, Baeksuk Chu
Journal of the Korean Society for Precision Engineering.2021; 38(7): 479. CrossRef

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Sensitivity Analysis and Optimum Design of Energy Harvesting Suspension System according to Vehicle Driving Conditions: Tae Dong Kim, Ji Hye Kim, Jin Ho Kim; J. Korean Soc. Precis. Eng. 2019;36(12):1173-1181.
Published online December 1, 2019; DOI: https://doi.org/10.7736/KSPE.2019.36.12.1173

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In this study, the sensitivity of the power generation effect of the applied linear generator of the energy harvesting suspension system under various input conditions was analyzed. The energy-harvesting suspension generates electric energy through energy harvesting using the road surface vibration energy during driving. Before analyzing the power generation effect, we analyzed the structure of the eight-pole Outer PM (Permanent Magnet) linear generator model using the electromagnetic suspension system to design the efficient generator, PIANO (Process Integration and Design Optimization). The ANSYS MAXWELL program was used to perform electromagnetic simulations of a linear generator model installed inside an energy-harvesting suspension to determine the power generation of the linear generator under various input conditions. The sensitivity of each input variable was compared by comparing the power generation effect of the energy-harvesting suspension device according to road displacement, frequency, and vehicle speed. The sensitivity to the road surface frequency was 1.9451, the sensitivity to the road surface amplitude was 1.0502, and the sensitivity to the vehicle speed was 0.6258. It is confirmed that the maximum sensitivity to the road surface displacement was demonstrated.

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Research on Key Issues of Consistency Analysis of Vehicle Steering Characteristics
Yanhua Liu, Xin Guan, Pingping Lu, Rui Guo
Chinese Journal of Mechanical Engineering.2021;[Epub] CrossRef
Shock-Absorber Rotary Generator for Automotive Vibration Energy Harvesting
Tae Dong Kim, Jin Ho Kim
Applied Sciences.2020; 10(18): 6599. CrossRef